1. Field of the Invention
The present invention relates generally to an Ethernet switching apparatus and method, and more particularly to an Ethernet switching apparatus and method using frame multiplexing and demultiplexing, which can correctly set a frame transmission sequence without information on the internal path of a switch fabric chip set by multiplexing a plurality of 1 gigabit Ethernet frames to one or more 10 gigabit Ethernet frames and demultiplexing one or more 10 gigabit Ethernet frames to a plurality of 1 gigabit Ethernet frames.
2. Description of the Prior Art
Generally, in order to implement an Ethernet switching apparatus, the configuration of a shared bus is used if a frame transmission speed of an input/output port is not high and a memory speed is low. On the other hand, an Ethernet switching apparatus is implemented using a switch fabric employing a crosspoint matrix so as to solve a bandwidth problem of the shared bus if the speed of an input/output port is higher than a gigabit level and a large capacity Ethernet switch is required. However, even in this case, the switch fabric must operate at the same speed as the speediest input/output port.
In the simplest prior art embodiment implementing such an Ethernet switching apparatus, it can be most realistically seen that low speed input streams are time division multiplexed to higher speed data streams. However, time division multiplexing (TDM) is disadvantageous in that frames must be configured to recognize respective input ports, and exclusive channels must be used due to the characteristics of TDM, thus decreasing the efficiency of bandwidth use.
Several methods and apparatuses have been proposed and used so as to overcome the disadvantage in the prior art.
For example, the U.S. Pat. No. 6,256,306 B1 (July, 2001) is proposed to provide scalability of network switches. In this patent, a bus-shaped switch node containing a route table constructed by joining local area network (LAN) standard technologies, such as high speed Ethernet, similar bridge protocols, etc., and a frame buffer, and unit switch modules having a plurality of Ethernet ports connected to the switch node are constructed in the form of an integrated circuit (IC). Further, if a plurality of unit switch modules are combined with LAN standard technologies, such as high speed Ethernet, similar bridge protocols, etc., an N*N atomic type switch mesh can be constructed, so an Ethernet network switch with very high scalability can be constructed. However, in the above method, the scalability of the network switch is very high, while a maximum processing speed per port obtained by a user port is limited to those of Ethernet ports of the unit switch modules. Moreover, this method is problematic in that the bus-shaped unit switch modules must have a processing capacity equal to or greater than 10 gigabits so as to provide 10 gigabit Ethernet ports to users.
Further, the implementation of a high speed switch architecture through the insertion of high speed media between a 2-gigabit backplane of a concentrator and a gigabit fiber optic Ethernet link is disclosed in U.S. Pat. No. 6,310,882 B1 (October, 2001). The object of this patent is to increase the efficiency of a fiber optic link by independently performing forwarding processing for transmission and reception packets in high speed media. However, the switch having the above architecture is problematic in that its maximum capacity and bandwidth are fundamentally limited due to the transmission speed of the fiber optic link.
Further, a network switch in which ATM ports and Ethernet ports are mixed is disclosed in U.S. Pat. No. 6,249,528 B1 (July, 2001). In this patent, an Ethernet frame format is different from an asynchronous transfer mode (ATM) format. Therefore, in order to reduce the number of ATM cell converters and the Ethernet frame converters required at each port, when an ATM port transmits packets to an Ethernet port, the ATM port transmits packets to a shared Ethernet frame converter through a crossbar switch to allow the packets to be converted into Ethernet frames, and thereafter the Ethernet frame converter outputs the Ethernet frames to a desired Ethernet port using the crossbar switch. On the other hand, when the Ethernet port transmits packets to the ATM port, the Ethernet port transmits the packets to a shared ATM cell converter through the crossbar switch to allow the packets to be converted into ATM cells, and thereafter the ATM cell converter transmits the ATM cells to a desired ATM port using the crossbar switch. This method is advantageous in that it can reduce the number of ATM cell converters and the Ethernet frame converters, while it is disadvantageous in that, since it uses the crossbar switch twice, packet converting ability per unit time of the crossbar switch is decreased as the frequency of packet transmission between the ATM port and the Ethernet port is increased.
Further, a packet switching fabric disclosed in U.S. Pat. No. 6,246,692 B1 (June, 2001) is constructed such that a ring pair comprised of a data ring and a control ring and unit switch modules accommodating a plurality of user ports are coupled to each other as a ring architecture, and an exclusive managing device for traffic management of the ring is inserted into the ring. Through the above construction, the switching fabric is operated such that a unit switch module having a medium and low speed user port executes traffic processing using a cut-through method, and a unit switch module having a Gbps-level port provides a service using a resource reservation allocation method so as to prevent the deterioration of the performance of an entire system. In this case, an exclusive protocol method is used in such traffic management. However, the switching fabric using the protocol method is limited in that the entire capacity of the switching fabric is determined according to the transmission speed of the ring which is a part constituting the core of the switching fabric, and is problematic in that it causes a burden of frame conversion due to the use of an exclusive device.
As described above, the conventional TDM method is problematic in that the efficiency of bandwidth use is decreased, and the switching fabric employing a ring architecture is problematic in that the transmission speed of the ring must be increased to be greater than 10 Gbps. Further, the network switch using a crossbar switch is problematic in that the processing speed of the crossbar switch is inevitably reduced to the maximum speed obtained by a port. The switching fabric using an exclusive device or an exclusive protocol for traffic management is problematic in that it requires an additional high speed switch, and a protocol converter for reconverting converted high speed packets into original Ethernet packets, and further requires an additional interface circuit for connection to a conventional chip set.